Photographic systems with polyvalent metal ions contiguous to the silver halide grains

ABSTRACT

A PHOTOGRAPHIC, SILVER HALIDE SYSTEM CONTAINING SILVER HALIDE GRAINS HAVING POLYVALENT IONS OCCLUDED THEREIN, SAID SILVER HALIDE SYSTEM HAVING A HALOGEN ACCEPTOR AND TRIVALENT OR TETRAVALENT METAL ION SALT CONTIGUOUS TO SAID POLYVALENT METAL-CONTAINING SILVER HALIDE GRAINS. IN THE PREFERRED EMBODIMENTS THE SILVER HALIDE GRAINS ARE FORMED IN ACIDIC MEDIA. IN ONE ASPECT, THE TRIVALENT OR TETRAVALENT METAL ION IMPROVES THE CHEMICAL DEVELOPING-OUT CHARACTERISTICS OF GOOD PRINT-OUT EMULSIONS.

United States Patent PHOTOGRAPHIC SYSTEMS WITH POLYVALENT METAL IONS CONTIGUOUS TO THE SILVER HALIDE GRAINS Robert E. Bacon, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y. No Drawing. Filed Apr. 7, 1967, Ser. No. 629,091 Int. Cl. G03c 1/02 U.S. Cl. 96-94 17 Claims ABSTRACT OF THE DISCLOSURE A photographic, silver halide system containing silver halide grains having polyvalent ions occluded therein, said silver halide system having a halogen acceptor and trivalent or tetravalent metal ion salt contiguous to said polyvalent metal-containing silver halide grains. In the preferred embodiments the silver halide grains are formed in acidic media. In one aspect, the trivalent or tetravalent metal ion improves the chemical developing-out characteristics of good print-out emulsions.

This invention relates to radiation-sensitive silver halide materials. In one aspect this invention relates to a silver halide emulsion containing silver halide grains with occluded polyvalent ions therein and having a halogen acceptor and a metal salt contiguous to said silver halide grains. In another aspect this invention relates to an improved photographic emulsion which has increased maximum density and increased contrast upon chemical development. In still another aspect this invention relates to an emulsion having good print-out characteristics which can also be chemically developed to an image record with high D and good contrast.

Emulsions which have good print-out characteristics and which can be chemically developed to provide a permanent record are known in the art. These emulsions generally contain silver halide grains which have been precipitated in the presence or trivalent or tetravalent metal ions. French patent 1,456,581 made available October 28, 1966, discloses several emulsions of this type. However, it is desirable to further improve the chemical developing-out characteristics of good print-out emulsions.

Therefore, it is an object of this invention to provide a novel photographic emulsion.

It is another object of this invention to provide novelradiation sensitive silver halide systems that can be used to prepare visible images directly by exposure to light.

It is another object of this invention to provide novel radiation-sensitive silver halide systems that can be chemically developed.

It is still another object of this invention to provide novel radiation-sensitive silver halide systems that can be utilized as either developing-out materials or print-out materials.

It is also an object of this invention to provide novel silver halide emulsions for preparing photographic proofs.

These and other objects of the invention are accomplished with radiation-sensitive silver halide systems containing silver halide grains formed in the presence of polyvalent metal ions, said silver halide system having contiguous to the polyvalent metal ion containing silver halide a halogen acceptor and trivalent or tetravalent metal salts.

In accordance with the invention the polyvalent metal ions are used in the precipitation or formation of the silver halide. Silver halide crystals are formed with polyvalent ions or atoms occluded therein. Typical suitable polyvalent metal ions include the trivalent metal ions such as those of antimony, bismuth, arsenic, gold, iridium, rho- "ice dium and the like, and tetravalent metal ions such as those of platinum, osmium, iridium and the like. The polyvalent metal ions or mixtures thereof can be suitably added with the water-soluble salt (e.g. silver nitrate) or the water-soluble halide (e.g. sodium or potassium iodide, bromide or chloride) that are combined to precipitate photographic silver halide. Likewise, the polyvalent ions can also be introduced into the silver halide precipitation vessel with a hydrophilic colloid such as gelatin. The polyvalent metal ions can be added to the system as watersoluble inorganic salts, as organo-metallic materials, as

complexes, or any other form of material that results in.

the availability of the polyvalent metal ions during the formation of the silver halide. The amount of polyvalent metal utilized can be widely varied, though at least 1 10- and more generally about 1X10 to about 2 mole percent based on the silver halide is used. The presence of the polyvalent metal ions in the silver halide grain can be observed analytically by successively washing the precipitated silver halide grains with a silver halide solvent such as an organic thioether or an alkali metal thiocyanate. If the polyvalent metal ions are only contiguous to the surface, substantially all of the ions will be observed in the analysis of the first washings while substantial amounts of polyvalent ions will be found in washings just prior to complete dissolution of the silver halide when the ions are occluded therein.

The emulsion containing the silver halide grains containing the polyvalent 'ions occluded therein is washed and the following addenda are added in accordance with the invention. A halogen acceptor and a trivalent or tetravalent metal ion salt are added to the emulsion. The trivalent or tetravalent metal ion salts, thus added, are contiguous to the silver halide grains and can be readily distinguished from the polyvalent ions occluded within the crystalline grain; for identification the trivalent or tetravalent metal ion salts can be removed by washing in an aqueous solutionfollowed by washing quickly with a silver halide solvent to remove the respective metal salts contiguous to the silver halide grains. Typical trivalent metal ion salts which can be added to the emulsion contiguous to the silver halide grains are those of antimony, bismuth, arsenic, gold, iridium, rhodium and the like. Typical tetravalent metal ion salts which can be added to the emulsion contiguous to the silver halide grains are those of platinum, osmium, iridium and the like. In the preferred embodiments of this invention metal salts of rhodium, iridium and platinum are placed contiguous to the silver halide grains to achieve very high D and maximum contrast.

The concentration of the trivalent or tetravalent metal ion salts utilized contiguous to the silver halide grains of this invention can be widely varied. Generally about 10 to about 500 mg./mole of silver and preferably about to 250 rug/mole of silver in the emulsion is utilized in the emulsion.

In preparing the silver halide used in the invention, the water-soluble silver salt and the water-soluble halide are reacted to precipitate the silver halide preferably under acidic conditions. The pH of the silver halide precipitation is typically less than 6 and preferably less than 5. Such acids as phosphoric, trifluoracetic, hydrobromic, hydrochloric, sulfuric and nitric are typically utilized in the silver halide precipitating media to maintain acidic conditions. The silver halide grains useful in the invention generally have an average grain size of about .01 to 10 microns, and more generally about .05 to 2 microns, in diameter.

Suitable silver halides include silver chloride, silver bromide, silver bromoiodide, silver chloroiodide, and silver chlorobromoiodide. The silver halide preferably is unfogged and contains at least 50% bromide, less than 10% iodide and less than 50% chloride on a molar basis. Both silver halide that forms latent image predominantly on the surface of the silver halide crystal or those that form latent images predominantly inside the silver halide crystal, such as those described in Davey and Knott, US. Pat. 2,592,250 issued Apr. 8, 1952, can be used in the materials of the present invention.

Various types of halogen acceptors can be used in the emulsion. However, nitrogen containing halogen acceptors are particularly useful in the invention. Typical nitrogencontaining halogen acceptors include the thioureas, hydrazines, urazoles, thiourazoles, and the like. Halogen acceptors of this type are disclosed in McBride, US. Pat. 3,287,137 issued Nov. 22, 1966. The preferred halogen accceptors are those such as Z-imidazolidinethione, 1- phenyl-S-mercaptotetrazole, thiosemicarbazide, tetramethylthiourea, 2-thiouracil, hydrazine, l-phenyl-2-imidazolidinethione, 1-methyl-2-mercaptoimidazole, thiourea, urazole, 3-thiourazole, 3,5-dithiourazole hydrazine salt, urazole sodium salt, 4-ethylurazole, 1,4-dibutylurazole and 3-thio-5-iminourazole. Such ureas, which include thioureas, urazoles, etc., as well as cyclic forms thereof, are merely illustrative halogen acceptors.

Other typical halogen acceptors that can be used in the invention include aromatic mercaptans such as thiosalicylic acid; hydroquinones such as hydroquinone, chlorohydroquinone, gentisic acid and t-butylhydroquinone; catechols such as phenyl catechol and t-butylcatechol; p-aminophenols such as N-methyl-p-aminophenol sulfate; 3-pyrazolidones such as 1-phenyl-3-pyrazolidone, 4-methyl-1- phenyl-3-pyrazolidone and 1phenyl-4,4-dimethyl-3-pyrazolidone; phenylenediamines; nitriles; phenols; glycine; sodium sulfite; alkaline materials such as borax, alkali metal hydroxide, etc.; and the like halogen acceptors well known to those skilled in the art.

The concentration of halogen acceptor utilized in the emulsions of the invention can be widely varied in accordance with usual practice. Usually, about .01 to 100 mole percent, and more generally about .1 to 25 mole percent, based on the silver halide in the emulsion is utilized.

The halogen acceptors are utilized contiguous to the silver halide in the present photographic system. Such halogen acceptors can be incorporated in the same photographic layer as the silver halide such as in the same emulsion layer, or in a layer adjacent to the silver halide.

The photographic silver halide system of the invention can comprise layers coated on a wide variety of supports in accordance with usual practice. Typical suitable supports include paper, polyethylene-coated paper, polypropylene-coated paper, cellulose acetate film, polyvinyl acetal film, polystyrene film, polyester films such as polyethylene terephthalate film, polycarbonate films, polyimide films and related films of resinous materials, as well as glass, metals and others.

I have found that silver halide grains formed in the presence of the polyvalent ions, when coated with addenda such as a halogen acceptor and a trivalent or tetravalent metal ion salt, yield highly sensitive materials which can be utilized as either print-out materials or as developing-out materials. The increased Dmsbx and increased contrast after chemical development are quite unexpected especially since increased concentrations of polyvalent ions used during the precipitation step give essentially no similar improvement in the image characteristics upon chemical development. Moreover, the extremely low photographic sensitivity in the absence of a halogen acceptor, coupled with the high susceptibility to print-out in the presence of a halogen acceptor were quite surprising, especially since most addenda which increase chemical developing-out properties decrease the print-out quality of an emulsion.

The unexpected characteristics exhibited by our photographic silver halide system lends itself very readily to the formation of photographic proofs. When a silver halide emulsion prepared as described herein is coated with a halogen acceptor and a trivalent or tetravalent metal ion salt, the print-out image is unstable to further over-all exposure. However, if the halogen acceptor is removed by washing or by treatment with an oxidizing agent such as bromine water, acidic permanganate, sodium hypochloride, N-bromosuccinimide, etc. after imagewise print-out exposure, a highly stable record is obtained. Alternatively, any method of imagewise halogen acceptor formation in the element followed by over-all light exposure also gives a stable record if the silver halide emulsion layer was coated without a halogen acceptor. In either case, image fading does not occur with continued exposure.

The invention can be further illustrated by the following examples, although it will be understood that the examples are included merely for purposes of illustration and are not intended to limit the scope of the invention unless otherwise indicated.

EXAMPLE 1 A radiation-sensitive gelatino silver chlorobromide (5 mole percent chloride and mole percent bromide) photographic emulsion is prepared by slowly adding simultaneously an aqueous silver nitrate solution and an aqueous alkali metal halide solution to an agitated aqueous gelatin solution at 50 C. at a pH of about 1.8 adjusted with nitric acid. The gelatin solution and the alkali metal halide solution also contain 7.5 mg. of (NH RhCl per mole of silver. The emulsion is washed in the usual manner. Five mole percent of the halogen acceptor, dithiourazole hydrazine salt, is added to the emulsion. The emulsion is divided into three portions; one portion is coated on a polyester (polyethylene terephthalate) film support with no further addenda; to the other portions is added respectively and mg. of rhodium trichloride per mole of silver before coating on a similar support.

The coatings are exposed through a step wedge with light from a high pressure mercury arc lamp through a Wratten 2C Filter, and developed for 4 minutes in Kodak 13-85 Developer, fixed, washed and dried. The following comparative results show the improvement in the emulsions of this invention.

Rhodium trichloride as a coating addendum Contrast Dmnx N one 1. 66 2. 12 100 mg./mole Ag 4. 6O 3. 24 150 mgJmole Ag 4. 60 3. 26

' EXAMPLE 2 Two emulsions of the type described in Example 1 are prepared containing 5 and 15 mg. of (NH RhCl per mole of silver in the gelatin solution and the alkali metal halide solution respectively. Five mole percent of the halogen acceptor, dithiourazole hydrazine salt, is added to each emulsion which is then respectively split again into two portions. One portion of each emulsion is coated on a photographic paper support with no further addenda; to the remaining portion is added 100 mg. of rhodium trichloride per mole of silver before coating on a similar support. Processing and exposure are carried out by the procedure of Example 1 except that the development is for 7 minutes in Kodak D-85 Developer. The following results show that increasing the amount of rhodium salt in the precipitation with or without additional rhodium salt as coating addendum does not give the improvements in developability.

Similar results are obtained when the silver halide is precipitated in the presence of K IrCl Bi(NO -5H O;

K lrCl and K OSCI 'EXAMPLE 3 A radiation-sensitive gelatino silver chlorobromide (5 mole percent chloride and 95 mole percent bromide) photographic emulsion is prepared by slowly adding simultaneously an aqueous solution of silver nitrate and an aqueous solution of alkali metal halides to an agitated aqueous gelatin solution containing 1.5 g. bismuth trinitrate pentahydrate per mole of silver at 30 C. at a pH of about 1.8 adjusted with nitric acid. Before coating, 0.7 mole percent of the halogen acceptor, dithiourazole hydrazine salt, is added to the emulsion, which is then split into portions; one portion is coated on a polyester, polyethyleneterephthalate film support with no further addenda; to the other portions were added the coating addenda as listed in the table before coating on a similar support.

The coatings were exposed through a stepwedge with light from a high pressure mercury arc lamp through a Wratten Filter, and developed for 2 /2 minutes in Kodak D85 developer, tfixed, washed and dried. The following results show the improvement in the emulsions of my invention.

The invention has been described with reference to certain embodiments thereof for purposes of comparison of the compounds of the invention, but it will be understood that variations and modifications of the invention can be made within the scope of the following claims.

I claim:

1. An improved radiation-sensitive, photographic silver halide system containing silver halide grains having polyvalent metal ions occluded therein, the improvement comprising the combination of at least .01 mole percent, based on silver, of a halogen acceptor other than gelatin contiguous to said grains and at least 75 mg. per mole, based on silver, of a trivalent or tetravalent metal ion salt contiguous to said silver halide grains.

2. A radiation-sensitive system according to claim 1 wherein said silver halide grains have trivalent or tetravalent metal ions occluded therein.

3. A radiation-sensitive system according to claim 1 wherein said silver halide grains have osmium, platinum, iridium, antimony, arsenic, bismuth, gold or rhodium ions or mixtures thereof occluded therein.

4. A silver halide system according to claim 1 wherein said silver halide grains are unfogged and have been formed in an acidic medium in the presence of watersoluble polyvalent metal ions.

5. A radiation-sensitive system according to claim 1 wherein said halogen acceptor is a nitrogen-containing halogen acceptor.

6. A radiation-sensitive system according to claim 1 wherein said metal ions contiguous to said grains are antimony, bismuth, arsenic, gold, iridium, rhodium, osmium or platinum ions or mixtures thereof.

7. A radiation-sensitive system according to claim 1 wherein said trivalent or tetravalent metal ions are water-soluble rhodium, iridium or platinum salts or mixtures thereof which have been added to the system after the formation of the silver halide grains.

8. A radiation-sensitive system according to claim 1 wherein said halogen acceptor is a direct-print halogen acceptor.

9. A radiation-sensitive system according to claim 1 wherein the halide of said silver halide grains is predominantly bromide.

10. A radiation-sensitive photographic system comprising silver halide grains formed in an acidic medium in the presence of water-soluble osmium, platinum, iridium, antimony, arsenic, bismuth, gold or rhodium salts or mixtures thereof and wherein at least about .01 mole percent, based on silver, of a direct-print halogen acceptor and at least about mg. per mole of silver of a water-soluble trivalent or tetravalent metal ion salt have been added to the system after the formation of said silver halide grains.

11. A radiation-sensitive system according to claim 10 wherein said water-soluble trivalent or tetravalent metal ion salts are osmium, platinum or iridium salts or mixtures thereof.

12. A radiation-sensitive system according to claim 10 wherein said trivalent or tetravalent metal ions are antimony, arsenic, bismuth, gold, iridium or rhodium salts or mixtures thereof.

13. A radiation-sensitive system comprising silver halide grains having trivalent or tetravalent metal ions occluded therein, at least 75 mg. per mole of silver of a water-soluble trivalent or tetravalent metal ion salt contiguous to said silver halide grains, gelatin and at least .01 mole percent, based on silver, of one other compound which is a halogen acceptor.

14. A silver halide emulsion according to claim 13 wherein said metal ion salt contiguous to the silver halide grains is an osmium, rhodium or iridium salt or mixtures thereof.

15. A silver halide emulsion according to claim 13 wherein said silver halide grains are substantially unfogged.

16. A silver halide emulsion according to claim 13 wherein the halide of said silver halide is less than 10% iodide and wherein said grains are formed in an acidic medium.

17. A photographic element comprising the radiationsensitive system of claim 1.'

References Cited UNITED STATES PATENTS 2,717,833 9/1955 Wark 96108 3,123,474 3/1964 Byrne 9694 3,219,452 11/1965 Hartouni 9694 3,367,778 2/1968 Berriman 96108 3,418,122 12/1968 Colt 96108 3,447,927 6/ 1969 Bacon et al 96107 3,457,072 7/1969 Ditzer et al. 9627 NORMAN G. TORCHIN, Primary Examiner J. R. HIGHTOWER, Assistant Examiner Z31 3? UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,57LL,625' Dated Agril 13, 1211 Inventor(s) Robert E. Bacon It is certified that error appears in the above-identified pate and that said Letters Patent are hereby corrected as shown below:

Column 1, line 1 1 (pa e 1 line 16 of th cation), "or trivalent" should ead ---of trivalenzf Column 3 line 2 a should a g iU-, llne 1 of the appllca Column L lines 6-? (pa 6 6 line 21 of 1: cation), "hypochloride" should re d. -hy'pochl0rite Column 14., lines El -55 (page 7 line 26 of th application) "merca toter'a. e tetraZo1e p zole should read mar-capto- Signed and sealed this 22nd day of August 1972 (SEAL) Attest:

ROBERT GOTTSCHALK EDWARD M.FLETCHER,JR.

Commissioner of Pai Attesting Officer 

